AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Understanding the Glottis Motion Effect on Aerosol Transport and Deposition in a Subject-Specific Human Upper Airway Configuration
JIANAN ZHAO, Yu Feng, Oklahoma State University
Abstract Number: 403 Working Group: Health-Related Aerosols
Abstract To precisely estimate the lung uptake of airborne toxic particles with different exposure conditions for health risk assessment, high-resolution data on how they transport and deposit in human respiratory systems are critically needed. Computational Fluid-Particle Dynamics (CFPD) models have been employed for such studies for decades. However, existing CFPD models assume the glottis is static during the breathing cycle. Indeed, glottis has the narrowest passage and generates a laryngeal jet and recirculation of airflows downstream in the trachea. The transient glottis motion, i.e., adduction and abduction within the breathing cycles, could enhance the pulmonary airflow unsteadiness and the resultant inhaled particle deposition, which have not been well studied. Therefore, a novel CFPD model was developed in this study with the capability of modeling the glottis motion using dynamic mesh. To explore the causal relationships between the glottis motion and the aerosol dynamics in a subject-specific upper airway model, simulations were performed with both rigid and dynamic glottises in a sinusoidal breathing cycle representing the resting condition. The glottis adduction and abduction were achieved by controlling the movement of each node of the dynamic mesh, which is validated by clinical data. Specifically, 45,236 particles were inhaled with their diameters equal to 0.5 microns. Numerical results indicate that the realistic glottis motion induces more particles passing through the throat and entering the tracheobronchial region. Numerical deposition results indicate that the glottis motion leads to airflow pattern variations compared with the rigid glottis setup. Subsequently, glottis motion generates lower DFs in the oral cavity, oropharynx, and larynx, but slightly higher DF in the glottis. Glottis adduction during exhalation results in more particle depositions than the rigid glottis case. In conclusion, the glottis motion shows significant influence on particle deposition predictions and must be considered in CFPD simulations in the future.